Backpack



FIG. 1 is a perspective view of a backpack showing my design.

FIG. 2 is a front view thereof.

FIG. 3 is a back view thereof.

FIG. 4 is a left view thereof.

FIG. 5 is a right view thereof.

FIG. 6 is a top view thereof; and,

FIG. 7 is a bottom thereof.

The broken line showing is included for the purpose of illustrating environment and forms no part of the claimed design. 

CLAIM The ornamental design for a backpack, as shown and described. 